Carolina Digital Repository (University of North Carolina at Chapel Hill), 2005
Previous research on the vasculature of tumor-bearing animals has focused upon the microvasculatu... more Previous research on the vasculature of tumor-bearing animals has focused upon the microvasculature. Magnetic resonance angiography (MRA) offers a noninvasive, complementary approach that provides information about larger vessels. Quantitative analysis of MRA images of spontaneous preclinical tumor models has not been previously reported. Eleven TgT 121 ;p53 +/-mice, which invariably develop choroid plexus carcinoma (CPC), and nine age-matched healthy controls were imaged using T1, T2, and a high-resolution 3D time-of-flight (TOF) MRA sequences at 3T. Tumors and vessels were segmented to determine tumor volume and vascular attributes, including number of terminal branches (TBC), vessel count (VC), and the average vessel radii (AVRAD) of MRA-visible vessels within the tumor. Differences in the vasculature between tumor-bearing animals and healthy controls were analyzed statistically. Although the spatial resolution of MRA prohibits visualization of capillaries, a high density of intra-tumor blood vessels was visualized in CPC mice. A significant increase in TBC and VC, but not AVRAD, was observed in CPCs when compared to normal controls. Both TBC and VC were highly correlated with tumor volume. This study represents the first MRA analysis of a spontaneous preclinical brain tumor model. Although the spatial resolution of MRA is less than histological analysis, MRA-obtained vascular attributes provide useful information with full brain coverage. We show that consistent tumor vasculature properties can be determined by MRA. Such methods are critical for developing preclinical therapeutic testing and will help guide the development of human brain tumor analyses.
Abstract 415: Lin28a Regulates Pathological Cardiac Hypertrophic Growth Through Pck2-mediated Enhancement of Anabolic Synthesis
Circulation Research, Aug 3, 2018
During pathological hypertrophy, the heart undergoes extensive metabolic changes prior to the ons... more During pathological hypertrophy, the heart undergoes extensive metabolic changes prior to the onset of structural remodeling, yet, it remains unknown whether and how this metabolic remodeling could contribute to cardiac hypertrophic growth. Here, we identified the RNA-binding protein Lin28a as a critical regulator of pathological cardiac hypertrophy and metabolic re-patterning. Cardiac specific deletion of Lin28a attenuated pressure overload-induced hypertrophy and cardiac dysfunction. Transcriptomics and metabolomic analysis highlighted roles for Lin28a in promoting cardiac glycolysis and anabolic biosynthesis. Mechanistically, Lin28a directly bound to mitochondrial phosphoenolpyruvate carboxykinase 2 ( Pck2 ) mRNA and positively modulated its transcript level. By utilizing the neonatal rat cardiomyocytes (NRCMs) hypertrophy model, we found that manipulation of Pck2 expression phenocopied the metabolic and hypertrophic phenotypes of manipulating Lin28a expression. Furthermore, epistatic analyses demonstrated that overexpression of Pck2 reversed the attenuation of norepinephrine-induced enhancement of cardiac glycolysis and cardiac hypertrophy by loss of Lin28a function, and knockdown of Pck2 suppressed Lin28a-induced increase in cardiac glycolysis and cardiomyocyte hypertrophic growth. Thus, our study revealed a critical role of Lin28a in the regulation of pathological cardiac hypertrophic growth through Pck2-mediated regulation of cardiac metabolism.
The p53 gene is the most frequent target of structural and functional genetic mutations in human ... more The p53 gene is the most frequent target of structural and functional genetic mutations in human cancer. Thus, considerable effort has been devoted to mapping the functional domains of p53 with regard to their impact on tumorigenesis in vivo. Studies have shown that the carboxy-terminal domain of p53 is sufficient for transformation in vitro. To determine whether a transdominant-negative p53 protein could be used to elicit a tissue-specific p53-nuU effect in vivo, we tested whether a carboxy-terminal p53 fragment (amino acids 302-390) could abolish p53-dependent apoptosis in an established tumor progression model. We showed previously that loss of p53-dependent apoptosis accelerates brain tumorigenesis in a transgenic mouse model. Here, we show that the same effect can be elicited by expressing a dominant-negative p53 protein tissue specifically in the presence of wild-type p53. Transgenic mice in which pRb function has been disrupted and that coexpress a p53 carboxy-terminal dominant-negative fragment (p53DD) develop aggressive brain tumors mimicking genetic loss of p53 in this model. Inactivation of endogenous p53, which we show to be complexed with p53DD, results in a reduction in apoptosis and acceleration of tumorigenesis. These studies establish a mechanism for tissue-specific knock out of p53 function in vivo.
Lin28a Regulates Pathological Cardiac Hypertrophic Growth Through Pck2-Mediated Enhancement of Anabolic Synthesis
Circulation, Apr 2, 2019
Background: Hypertrophic response to pathological stimuli is a complex biological process that in... more Background: Hypertrophic response to pathological stimuli is a complex biological process that involves transcriptional and epigenetic regulation of the cardiac transcriptome. Although previous studies have implicated transcriptional factors and signaling molecules in pathological hypertrophy, the role of RNA-binding protein in this process has received little attention. Methods: Here we used transverse aortic constriction and in vitro cardiac hypertrophy models to characterize the role of an evolutionary conserved RNA-binding protein Lin28a in pathological cardiac hypertrophy. Next-generation sequencing, RNA immunoprecipitation, and gene expression analyses were applied to identify the downstream targets of Lin28a. Epistatic analysis, metabolic assays, and flux analysis were further used to characterize the effects of Lin28a and its downstream mediator in cardiomyocyte hypertrophic growth and metabolic remodeling. Results: Cardiac-specific deletion of Lin28a attenuated pressure overload–induced hypertrophic growth, cardiac dysfunction, and alterations in cardiac transcriptome. Mechanistically, Lin28a directly bound to mitochondrial phosphoenolpyruvate carboxykinase 2 ( Pck2 ) mRNA and increased its transcript level. Increasing Pck2 was sufficient to promote hypertrophic growth similar to that caused by increasing Lin28a, whereas knocking down Pck2 attenuated norepinephrine-induced cardiac hypertrophy. Epistatic analysis demonstrated that Pck2 mediated, at least in part, the role of Lin28a in cardiac hypertrophic growth. Furthermore, metabolomic analyses highlighted the role for Lin28a and Pck2 in promoting cardiac biosynthesis required for cell growth. Conclusions: Our study demonstrates that Lin28a promotes pathological cardiac hypertrophy and glycolytic reprograming, at least in part, by binding to and stabilizing Pck2 mRNA.
Carolina Digital Repository (University of North Carolina at Chapel Hill), 2012
The majority of human high grade serous epithelial ovarian cancer (SEOC) is characterized by freq... more The majority of human high grade serous epithelial ovarian cancer (SEOC) is characterized by frequent mutations in p53 and alterations in the RB and FOXM1 pathways. A subset of human SEOC harbors a combination of germline and somatic mutations as well as epigenetic dysfunction for BRCA1/2. Using Cre-conditional alleles and intrabursal induction by Cre-expressing adenovirus in genetically engineered mice, we analyzed the roles of pathway perturbations in epithelial ovarian cancer initiation and progression. Inactivation of RB-mediated tumor suppression induced surface epithelial proliferation with progression to stage I carcinoma. Additional biallelic inactivation and/or missense p53 mutation in the presence or absence of Brca1/2 caused progression to stage IV disease. As in human SEOC, mice developed peritoneal carcinomatosis, ascites, and distant metastases. Unbiased gene expression and metabolomic profiling confirmed that Rb, p53, and Brca1/2-triple mutant tumors aligned with human SEOC, and not with other intraperitoneal cancers. Together, our findings provide a novel resource for evaluating disease etiology and biomarkers, therapeutic evaluation, and improved imaging strategies in epithelial ovarian cancer.
Carolina Digital Repository (University of North Carolina at Chapel Hill), 2016
It has been long recognized that the mammalian heart loses its proliferative capacity soon after ... more It has been long recognized that the mammalian heart loses its proliferative capacity soon after birth, yet, the molecular basis of this loss of cardiac proliferation postnatally is largely unknown. In this study, we found that cardiac ErbB2, a member of the epidermal growth factor receptor family, exhibits a rapid and dramatic decline in expression at the neonatal stage. We further demonstrate that conditional ablation of ErbB2 in the ventricular myocardium results in upregulation of negative cell cycle regulators and a significant reduction in cardiomyocyte proliferation during the narrow neonatal proliferative time window. Together, our data reveal a positive correlation between the expression levels of ErbB2 with neonatal cardiomyocyte proliferation and suggest that reduction in cardiac ErbB2 expression may contribute to the loss of postnatal cardiomyocyte proliferative capacity.
Carolina Digital Repository (University of North Carolina at Chapel Hill), 2016
Direct conversion of fibroblasts into induced cardiomyocytes (iCMs) offers an alternative strateg... more Direct conversion of fibroblasts into induced cardiomyocytes (iCMs) offers an alternative strategy for cardiac disease modeling and regeneration. During iCM reprogramming, the starting fibroblasts must overcome existing epigenetic barriers to acquire the CM-like chromatin pattern. However, epigenetic dynamics along this reprogramming process have not been studied. Here, we took advantage of our recently generated polycistronic system and determined the dynamics of two critical histone marks, H3K27me3 and H3K4me3, in parallel with gene expression at a set of carefully selected cardiac and fibroblast loci during iCM reprogramming. We observed reduced H3K27me3 and increased H3K4me3 at cardiac promoters as early as day 3, paralleled by a rapid significant increase in their mRNA expression. In contrast, H3K27me3 at loci encoding fibroblast marker genes did not increase until day 10 and H3K4me3 progressively decreased along the reprogramming process; these changes were accompanied by a gradual decrease in the mRNA expression of fibroblast marker genes. Further analyses of fibroblast-enriched transcription factors revealed a similarly late deposition of H3K27me3 and decreased mRNA expression of Sox9, Twist1 and Twist2, three important players in epithelial-mesenchymal transition. Our data suggest early rapid activation of the cardiac program and later progressive suppression of fibroblast fate at both epigenetic and transcriptional levels. Additionally, we determined the DNA methylation states of representative cardiac promoters and found that not every single CpG was equally demethylated during early stage of iCM reprogramming. Rather, there are specific CpGs, whose
Proceedings of the National Academy of Sciences of the United States of America, Oct 10, 2013
Data deposition: The microarray raw data reported in this paper have been deposited in the Gene E... more Data deposition: The microarray raw data reported in this paper have been deposited in the Gene Expression Omnibus (GEO) database, www.ncbi.nlm.nih.gov/geo (accession no. GEO26069).
Supplementary Figure 5 from Perturbation of Rb, p53, and Brca1 or Brca2 Cooperate in Inducing Metastatic Serous Epithelial Ovarian Cancer
PDF file - 253K, Gene expression analysis
Supplementary Figure 2 from Perturbation of Rb, p53, and Brca1 or Brca2 Cooperate in Inducing Metastatic Serous Epithelial Ovarian Cancer
PDF file - 255K, Immunohistochemical staining for CA125, WT1 and calretinin
Supplementary Figure 4 from Perturbation of Rb, p53, and Brca1 or Brca2 Cooperate in Inducing Metastatic Serous Epithelial Ovarian Cancer
PDF file - 325K, Nuclear p53 expression correlates positively with loss of wild type allele in se... more PDF file - 325K, Nuclear p53 expression correlates positively with loss of wild type allele in serous epithelial ovarian carcinomas in p53m/+ mutant mice
Down-regulation of Beclin1 promotes direct cardiac reprogramming
Science Translational Medicine, Oct 21, 2020
Beclin1 suppresses induced cardiomyocyte reprogramming through an autophagy-independent, Wnt sign... more Beclin1 suppresses induced cardiomyocyte reprogramming through an autophagy-independent, Wnt signaling–dependent pathway.
Supplementary Figure 5 from Perturbation of Rb, p53, and Brca1 or Brca2 Cooperate in Inducing Metastatic Serous Epithelial Ovarian Cancer
PDF file - 253K, Gene expression analysis
Supplementary Figure 2 from Perturbation of Rb, p53, and Brca1 or Brca2 Cooperate in Inducing Metastatic Serous Epithelial Ovarian Cancer
PDF file - 255K, Immunohistochemical staining for CA125, WT1 and calretinin
Supplementary Figure 4 from Perturbation of Rb, p53, and Brca1 or Brca2 Cooperate in Inducing Metastatic Serous Epithelial Ovarian Cancer
PDF file - 325K, Nuclear p53 expression correlates positively with loss of wild type allele in se... more PDF file - 325K, Nuclear p53 expression correlates positively with loss of wild type allele in serous epithelial ovarian carcinomas in p53m/+ mutant mice
We observed an increase in mortality post-myocardial infarction or ischemia/reperfusion (I/R) in ... more We observed an increase in mortality post-myocardial infarction or ischemia/reperfusion (I/R) in type 2 diabetic mice. We also found a reduction of plasma and heart miR-24 levels in diabetic mice. Systemic enrichment of miR-24 in db/db mice or cardiomyocyte-specific overexpression of miR-24 in wild-type (WT) mice significantly reduced myocardial infarct size and alleviated cardiac injury. The possible mechanism underlying miR-24–based therapeutics in diabetic I/R may involve O-GlcNac transferase (OGT)–mediated heart protein O-GlcNAcylation, autophagy-related gene 4a (ATG4A)–mediated autophagy, and Bcl-2-like protein 11 (BIM)–mediated apoptosis.
Figure 3: Overexpression of miR-24 Ameliorates Diabetic Ischemia/Reperfusion Injury
<b>(A)</b> Schematic protocol of miR-24 delivery and I/R surgery. <b>(B)</b&... more <b>(A)</b> Schematic protocol of miR-24 delivery and I/R surgery. <b>(B)</b> Quantitative polymerase chain reaction analysis of miR-24 expression in hearts of db/db mice treated with mimic control (n = 6) or treated with miR-24 mimic (n = 6) for 2 weeks (normalized to U6). <b>(C)</b> Myocardial infarction size assessed following in vivo I/R (20 min LAD ligation and 3 h reperfusion) after treatment with miR-24 mimic (5 mg/kg) or scramble control intravenously, 2 weeks before LAD ligation. Representative images of myocardial tissue slices stained with Evans blue and triphenyl tetrazolium chloride. <b>(D)</b> Quantitation of infarct risk area. <b>(E)</b> Quantitation of infarct area expressed as percentage of the nonperfused risk area during coronary occlusion. <b>(F)</b> Enzyme-linked immunosorbent assay analysis of fasting plasma insulin levels in WT and db/db mice with without miR-24 mimic delivery (n = 8 to 10). <b>(G)</b> Fasting plasma glucose levels in db/db mice with without miR-24 mimic delivery (n = 10 to 12) (paired <i>t</i> test). Abbreviations as in Figure 1.
Figure 1: Diabetes Exacerbates Myocardial Infarction and Ischemia/Reperfusion Injury
<b>(A)</b> Comparison of fasting blood glucose levels in diabetic mouse models (n = 1... more <b>(A)</b> Comparison of fasting blood glucose levels in diabetic mouse models (n = 10 to 12). <b>(B)</b> Enzyme-linked immunosorbent assay analysis of fasting plasma insulin levels in diabetic mouse models (n = 8 to 10). <b>(C to E)</b> Comparison of infarct size between wild-type (WT) and db/db (leptin receptor knockout) mice subjected to ischemia for 20 min and reperfusion for 3 h. <b>(F)</b> Survival curve (log-rank [Mantel-Cox] test) of WT, streptozotocin (STZ)-induced type 1 diabetes (with or without insulin therapy), and db/db (with or without insulin therapy) subjected to 20 min ligation of left anterior descending coronary artery (LAD) followed by ischemia/reperfusion (I/R) for 4 weeks.
Abstract 415: Lin28a Regulates Pathological Cardiac Hypertrophic Growth Through Pck2-mediated Enhancement of Anabolic Synthesis
Circulation Research, 2018
During pathological hypertrophy, the heart undergoes extensive metabolic changes prior to the ons... more During pathological hypertrophy, the heart undergoes extensive metabolic changes prior to the onset of structural remodeling, yet, it remains unknown whether and how this metabolic remodeling could contribute to cardiac hypertrophic growth. Here, we identified the RNA-binding protein Lin28a as a critical regulator of pathological cardiac hypertrophy and metabolic re-patterning. Cardiac specific deletion of Lin28a attenuated pressure overload-induced hypertrophy and cardiac dysfunction. Transcriptomics and metabolomic analysis highlighted roles for Lin28a in promoting cardiac glycolysis and anabolic biosynthesis. Mechanistically, Lin28a directly bound to mitochondrial phosphoenolpyruvate carboxykinase 2 ( Pck2 ) mRNA and positively modulated its transcript level. By utilizing the neonatal rat cardiomyocytes (NRCMs) hypertrophy model, we found that manipulation of Pck2 expression phenocopied the metabolic and hypertrophic phenotypes of manipulating Lin28a expression. Furthermore, epis...
Direct lineage conversion offers a new strategy for tissue regeneration and disease modelling. De... more Direct lineage conversion offers a new strategy for tissue regeneration and disease modelling. Despite recent success in directly reprogramming fibroblasts into various cell types, the precise changes that occur as fibroblasts progressively convert to the target cell fates remain unclear. The inherent heterogeneity and asynchronous nature of the reprogramming process renders it difficult to study this process using bulk genomic techniques. Here we used single-cell RNA sequencing to overcome this limitation and analysed global transcriptome changes at early stages during the reprogramming of mouse fibroblasts into induced cardiomyocytes (iCMs). Using unsupervised dimensionality reduction and clustering algorithms, we identified molecularly distinct subpopulations of cells during reprogramming. We also constructed routes of iCM formation, and delineated the relationship between cell proliferation and iCM induction. Further analysis of global gene expression changes during reprogrammin...
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Papers by Chaoying Yin